1. The Mechanics of HTTP Requests and Responses and network connections

2. Slide 2 TELL ME ALL THAT YOU KNOW ABOUT GET AND POST! TELL ME ALL THAT YOU KNOW ABOUT MIME TYPES TELL ME ALL THAT YOU KNOW ABOUT XML

3. Slide 3 50,000 Foot Flyover Most of you have some understanding of networking and service-based. Here we will delve into the mechanics of developing “network-aware” applications that consume web services No matter the language and operating system, we make requests and process responses using a disconnected or connected protocol

4. Slide 4 Connected and Disconnected Protocols Using TCP, we establish connections and then read and write data over those connections SMTP, FTP all use TCP connections Using HTTP, we make requests and responses SOAP lives on top of HTTP Most restful applications are based on HTTP Web services We will focus our energy on HTTP layers

5. Slide 5 HTTP Requests and Responses No matter the language or development environment HTTP requests and responses work the same way We talked about the HttpRequest and HttpResponse objects in IS 360 with JavaScript PHP,.NET, Java, all have their implementations of HTTP requests and responses

6. Slide 6 HTTP Requests (Parts) Type: GET or POST Header Content-Type Content-Length Payload

7. Slide 7 HTTP Requests (ContentType)_ It appears in the HTTP header to describe the data in the payload envelope HTML XML PDF https://www.sitepoint.com/web- foundations/mime-types-complete-list/ https://www.sitepoint.com/web- foundations/mime-types-complete-list/

8. Slide 8 Requests and Responses (Other Protocols) Web services (SOAP and WSDL) are just protocols that send structured requests and get responses Often layered on top of HTTP They have different headers and an XML Content-Type We will look at these higher layers later in the next section At least how to consume Web Services

9. Slide 9 General Steps Prepare the HTTP request GET or POST Encoding Data Send the request Get the response Process the response

10. Slide 10 Java Java implements the HTTP request and response library as just another Java library (named java.net)

11. Slide 11 Java

12. Slide 12 PHP HTTP requests and responses are built in through another library There are several extension libraries too

13. Slide 13 PHP

14. Slide 14.NET

15. Slide 15 The.net Communications Framework

16. Slide 16 The.net Communications Framework

17. Slide 17 GET and POST HTTP requests are always done in one of two ways. Remember the basics from IS 360 GET arguments and data are sent via the URL as parameters POST arguments and data are sent via the HTTP header

18. Slide 18 GET and POST I’ll go through the mechanics of both using C# and demos as usual ASP Tracing helps us see how ASP builds requests and responses After you see what ASP does, we will see how to do this programatically

19. Slide 19 GET Illustration

20. Slide 20 POST Illustration

21. Slide 21 Getting at the HTTP Request and Response Data In ASP, we can get at the HTTP request, headers, form information, query strings, and server variables through predefined objects Other development environments operate similarly Request Request.Headers Request.Form Request.ServerVariabes

22. Slide 22 Getting at the Data All of these lists are of type System.Collections.Specialized.NameValueColl ection Items can be referenced by string key or ordinal index The values are text strings

23. Slide 23 Getting at the Data

24. Slide 24 You have seen how the ASP fabric implements and uses the GET and POST Now we will construct our own web requests and process them We will do so with both desktop and web applications to show that services are services It has nothing to do with a web browser Creating HTTP Requests

25. Slide 25 Why do this by hand? Because this is how services work We are automating processes through well- known services A Web service to get the weather

26. Slide 26 Ways to get data Restful GETPOSTSOAP

27. Slide 27 Preparing a GET The WebReqeust class has a method named Create to create the request. The argument contains the request URL The Method property should be set to GET or POST

28. Slide 28 Processing a GET The WebReqeust has a method named GetResponse This method sends the request and gets the response code It does not read the data Response.ContentType gets the format of the content Response.ContentLength gets the size of the data evenelope

29. Slide 29 Processing the GET Response We need to create a stream to read the data Call GetResponseStream() to get the stream for the response Create a StreamReader to get the response data Call StreamReader.ReadToEnd() to read the data stream

30. Slide 30 Processing the GET Response Execute the request and get response information

31. Slide 31 Reading the GET data Reading the HTTP response data is similar to reading a file You read a stream And you can read that stream differently into different objects

32. Slide 32 Reading the GET data (example) Use GetResponseStream() to create a StreamReader Same reader that you have used before

33. Slide 33 Preparing a POST Create a WebRequest as before Set the Method to POST Set the ContentType to describe the format of the body Add Headers to the collection Instead of calling GetResponseStream, we call GetRequestStream Write to this stream to send the HTTP message Close the writer to complete the response Then call GetResponse as before

34. Slide 34 A Post message

35. Slide 35 SOAP Encapsulates an XML document for the purpose of serialization SOAP messages are exchanged between providers and consumers SOAP is a message envelope containing an XML document Consumers send SOAP requests to providers Requests are method calls serialized into an XML document Providers send responses to consumers in the form of another XML document All of this happens behind the scenes and is not that significant to the developer

36. Slide 36 WSDL A WSDL document fully describes a Web service All methods are defined Method signatures are also defined A WSDL document is a well-formed and valid XML document A WSDL document is almost always generated automatically They become very complex very quickly.NET uses the WSDL document along with Intellisense technology to display member calling conventions (signature prototypes)

37. Slide 37 Using the Service Infrastructure You saw how to create a SOAP message by hand What a pain So we have a SOAP layer of abstraction that makes the process of a remote procedure call much easier

38. Slide 38 It’s based on a WSDL document A WSDL document describe the http://wsf.cdyne.com/WeatherWS/Weather.a smx?op=GetCityForecastByZIP http://wsf.cdyne.com/WeatherWS/Weather.a smx?op=GetCityForecastByZIP http://wsf.cdyne.com/WeatherWS/Weather.a smx?WSDL http://wsf.cdyne.com/WeatherWS/Weather.a smx?WSDL

39. Slide 39 Steps to use a service Add a service reference to the WSDL document Call the methods as ordinary methods

40. Slide 40 Add a Web Reference

41. Slide 41 Add a Web Reference

42. Slide 42 Web Service Example Looks like a local method call

43. Slide 43 Welcome to WCF We configure most “communication things”

44. Slide 44 The Role of App.Config App.Config operates similarly to Web.Config Here, it’s used to configure a Web Service All of this appears inside of We could also hardcode this

45. Slide 45 App.config (Bindings) Bindings define the transport protocol details needed for a client to communicate with a service Predefined (provided) bindings Custom bindings

46. Slide 46 App.config (Bindings) Here we bind to three different services

47. Slide 47 App.config (Endpoints) Endpoints allow clients to access a Web service Consists of An address (URL that points to the service) Name of a binding (how to communicate with the endpoint) The contract defining the methods available

48. Slide 48 Configure App.Config

49. Slide 49 Processing Data (Introduction)